quartz -Quartz is a modular approach to a casting bar addon.It comes with a swing timer bar and a cast bar which predicts lag so if your lagging a little bit it will so you round about the time it will finish. There is an example below showing what i mean.

there are many more uses for this addon like: It will displays a tiny spark-bar to show your Global Cooldown near the cast bar. Helpful for those who'd rather not squint at their action bars to see when they can cast again.